Circuit breaker



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CIRCUIT BREAKER Filed June 26, 1957 s Sheets-Sheet 1 INVENTOR.

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CIRCUIT BREAKER Filed June 26, 1957 3 Sheets-Sheet 2 l nji 7 52 42 I I m 5% m INVENTOR.

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CIRCUIT BREAKER Filed June 26, 1957 3 Sheets-Sheet 5 '9 TTOKNEXS United States Patent CIRCUIT BREAKER William H. Middendorf, Covington, Ky., assignor to The Wadsworth Electric Manufacturing Company, Inc., Covington, Ky., a corporation of Kentucky Application June 26, 1957, Serial No. 668,166

21 Claims. (Cl. 200-116) This invention relates to an improved electric circuit breaker of the type adapted for installation in household distribution circuits or the like.

Various types of circuit breakers have beeen available which are automatically operable in event of circuit overload to open the circuit in which they are installed and thereby terminate a hazardous circuit condition. A principal objective of this invention has been to provide a circuit breaker of this general type but which, without sacrifice of reliability of operation or sensitivity to overload response, may be manufactured and assembled from a fewer number of parts and at less expense than the devices which have been commercially available. In this connection, an objective of the invention has been to provide a simplified circuit breaker having current-responsive means which readily may be calibrated prior to assembly of the structure whereby fabrication and assembly of the unit is facilitated.

A further objective has been to provide a circuit breaker which, by virtue of the nature of the construction, is smaller than circuit breakers now available which are of comparable function but in which the current-responsive member is of relatively enlarged size so as to provide greater reliability, ruggedness, and sensitivity of response of the individual circuit breakers in conjunction with a marked reduction in the over-all size of the load centers in which a plurality of such circuit breakers are installed.

A further objective of the present invention has been to provide a circuit breaker construction in which a high degree of precision in the shape and configuration of the parts is not required, which parts readily may be assembled for movement relative to one another within a casing without rigid attachment of any of the same thereto.

A still further objective of the present invention has been to provide a circuit breaker construction which is readily adapted easily and conveniently for two pole service as required, wherein the installation of a simple pin between the breakers is eifective to cause tripping of one of the breakers of a two pole assembly promptly in response to tripping of the other of the breakers of an assembly in consequence of overload in the circuit leg which is served thereby.

Other objectives of the invention and various features and advantages of the present construction appear in the following detailed description of the drawings of a circuit breaker constructed in accordance with this invention. In the drawings:

Figure 1 is a sectional elevation showing the operative parts of the mechanism in the positions they occupy when the circuit breaker is in the closed circuit condition;

Figure 2 is a view similar to Figure 1 but showing the parts in the positions they occupy when the circuit breaker is in the open circuit condition;

Figure 3 is a sectional view taken on the line 33 of Figure 1 transversely through a circuit breaker;

Figure 4 is a fragmentary sectional view taken on the line 4-4 of Figure 1;

Figures 5, 6,- and 7 are diagrammatic views showing the relationships which the operating parts occupy during various stages of manual operation of the circuit breaker from closed circuit to open circuit condition, in which views Figure 6 shows the parts at an intermediate stage of movement between the closed circuit position shown in Figure 5 and the open circuit position shown in Figure 7;

Figures 8 and 9 are diagrammatic views showing the relationships and directions of movement of the parts during resetting of the circuit breaker from open circuit to closed circuit position, in which views the parts are shown in Figure 8 just after the operating handle has commenced to move in a resetting direction and Figure 9 shows the parts at a subsequent stage of resetting just before resetting is completed. From the position shown in Figure 9 the parts move to the closed-circuit position shown in Figure 1.

Figure 10 is a sectional view of a supplemental means for calibrating a circuit breaker of the present invention after assembly of the parts thereof;

Figure 11 is a fragmentary view showing a pair of circuit breakers equipped with a common trip element; and

Figure 12 is a view similar to Figure 11 showing the function of the common trip element in mechanically tripping one breaker of a pair in consequence of automatic tripping of the other breaker of a pair.

The circuit breaker shown in the drawings comprises a carrier 1, a stationary contact 2, a movable contact 3 which is engageable with the stationary contact and which is supported upon a switch arm 4. The switch arm, in turn is associated with a bimetal member 5 which is thermally responsive to current overload to control a latch. Upon releas from the latch, the switch arm is biased to open circuit position by an actuating spring 6 and is movable manually through a handle 7. All of the parts are contained within a case 8 which may be of molded plastic or electrically insulative material and which may be made into halves joined together after the parts have been laid in place. The case contains line terminals 9 and 10 at its opposite line ends. These terminals may be of any suitable type; in the construction shown the terminal 10 is of the screw type to which a circuit conductor may be fastened, while terminal 9 is of the jaw type adapted for frictional interengagement with a blade or bus bar provided at a load center where the circuit breaker is to be installed.

For purposes of convenience, the mechanical or structural relationship of the parts will first be explained, followed by description of the manner in which the parts cooperate with one another in the various phases of circuit breaker operation. 1 a

Carrier 1 is a bifurcated member comprising side plates 12, 12 which are spaced apart as shown in Figure 3 so as to reside adjacent the side walls of the casing 8. Side plates 12 of the carrier are interconnected to one another at the top by a cross plate 13. The carrier may be blanked and formed as a single piece of metal or may be formed as a plastic molding since it has no current carrying function.

Side walls 12 of the carrier 1 respectively contain elon gated slots 14 near the upper cross portion 13 of the unit. These slots are in alignment with one another respectively to receive pivot lugs 15 extending inwardly toward one another from the side walls of the case 8 as shown in Figure 3. If the carrier 1 is of stamped sheet metal, the portions marginally adjacent the slots 14 may be flanged inwardly as at 16 to provide adequate bearing surfaces for the pivot lugs 15 which are preferably formed as integral portions of the plastic case 8.

Side walls 12 of the carrier also are respectively pro vided with bearing slots 17 through which the switch arm 4and current-responsive bimetal member 5 are associated with the carrier 1. In this construction, the slots 17, which may be flanged inwardly as at 18 to provide adequate bearing surfaces, receive a pivot rod 19 which extends across the carrier 1 and beyond the outer faces of the side plates 12 thereof, the ends of rod 19 clearing the side walls of case 8. The slots 14, as shown, reside on a generally vertical axis, while the slots 17 of the carrier I reside on an axis slightly declined to the right, the reasons for which are subsequently explained. It will be noted that slots 17 are offset fromslots 14, below and to the left thereof as shown in Figure 2.

A latch bar 29 extends between and across the side walls 12 of the carrier, below slot 14 and approximately at the elevation of slots 17, although it will be understood from the subsequent description that the geometry of the system readily may be varied. Latch member 20 is fastened rigidly to side plates 12iof the'carrier, such molded as by piercing the side plates to permit the latch piece to extend therethrough and be secured thereto or in other suitable manner. The latch bar is preferably made of stainless steel or similar metal which has a low friction characteristic and is reasonably resistant to wear.

Switch arm 4 is located between the side plates 12 of the contact carrier 1 and, at its lower end, the movable contact 3 is fastened rigidly thereto. The switch arm is bent or grooved transversely'as at 21 to provide a seat for pivot rod 19 and also includes a portion extending therebyond which terminates in an eye portion 22 adapted for reception of one end of the tension spring 6. The opposite end of the tension spring is sustained upon a cross pin member 24 formed as a part of case 8. The portions of the pivot rod 19 projecting beyond the side plates of the carrier 1 respectively reside above but adjacent cooperable camming surfaces 23, 23 which are formed as integral parts of the respective side walls of case 8. These camming surfaces are positioned to effect relative movement of pivot rod 19 in slot 17 toward the latch bar 20 of the carrier as the carrier is moved in a downward direction as permitted'by slots 14.

The current-responsive bimetal member 5 is in the form of an inverted U and one end is fastened rigidly to the switch arm 4 as by welding. The endwise portion of the bimetal member may extend across the pivot rod concavity 21 so as tocomplete the journal for the pivot rod. The opposite endwise portion 25 of, the bimetal is in electrical connection with line terminal 10 through a flexible conductor 26.

Portion 25 of the bimetal is equipped with a latch member 27 which is cooperable with the latch bar 20 of the contact carrier 1. Latch member 27 may be in the form of a piece of metal fastened to the bimetal or struck therefrom to present a latching surface or, in the alternative, the latching surface of the member 27 may be furnished as a part of a device which is magnetically responsive to overloads of an instantaneous nature to supplement the protection which is afiorded by thermal response of the bimetal member. For magnetic protection, an arrangement may be used such as that disclosed and claimed in U.S. Patent 2,716,679, comprising a yoke 28 of magnetic metal which .is in the form of a U straddling the bimetal member, and an armature 29 having one end loosely or hingedly associated with one side arm of the U-shaped magnetic yoke as'at 30, while the other end of the armature extends beyond and in spaced relation to the other side of the magnetic yoke for engagement with an edge of the carrier 1 when the parts are in the circuit-closed position shown in Figure 1.

The lower portion of the casing cavity contains a cross wall 31 which actsas astop, its one face limiting movement of the switch arm 4 as it swings away from contact 2 to open position while the opposite face limits movement of carrier 1 as it swings about its pivot lugs 15.

Handle 7 at the upper part of the case is of the shielding rocker type and includes a side arm portion 33 which is pivotally connected to a side wall portion of the case as at 34 and a shield portion 35 which extends on an arc about the pivot 34 beneath a top wall portion 36 of the case which is of complementary configuration but which is slotted as at 37. The handle proper, 7, extends from the shield 34 through the slot.

Beneath the shield portion 34 the handle contains two projections 38 and 39 spaced apart from one another. Of these, element 38 provides an edge 40 which is engageable with the upper surface of cross wall 13 of the carrier for depressing the carrier as the handle is rocked in one direction (i.e., clockwise, Figure 1), and a face portion 41 which is engageable with an edge portion 42 of the crosswall of the carrier for rocking the carrier about its pivots 15 when the handle is moved in an opposite direction. To avoid undue wear, the edge portion 42 of the carrier may be in the form of a flange bent downwardly from the transverse edge of the cross wall 13 of the carrier.

Member 39 of the handle constitutes an abutment which is engageable with a finger 43 projecting from the opposite end of the cross wall 13 for shifting the handle to denote a tripped condition of the breaker in consequence of movement of the carrier incidental to the tripping of the breaker. The shield portion of the handle may be provided with a detent 44 for engagement with a recess in the adjacent top wall 36 of the case to pre vent inadvertent movement of the handle from the on position.

In the construction shown, the stationary contact 2 is fastened against the face of a metallic conductor 45 which is formed as a projection of a stamping comprising the jaws which form the line terminal 9. To-hold these jaws yieldably against over-spreading, they are straddled by a spring metal clip 46. The terminal piece 9 to which the stationary contact 2 is fastened may be held in place in the casing by suitable recessing, beneath a cross wall 47 whereby the circuit breaker is supported mechanically at one end by a conductive prong or blade over which the jaws forming the terminal 9 have been engaged. The opposite end of the circuit breaker may be supported mechanically by suitable means such as the yieldable clip 43 which is selectively adapted for insertion in a panelboard aperture in accordance with the rated capacity of the circuit breaker as disclosed and claimed in my copending patent application Serial No. 633,367 filed January 9, 1957. V

For escape of hot gases formed by arcing incidental to opening of the contacts under load, aperture 57 beneath the stop wall'31 and aperture 58 adjacent mounting clip 48 provide a gas path.

MODE OF OPERATION Automatic release In the circuit-closed position of the parts, as shown in Figure l, the latching surface 27 of the bimetal 5 is en gaged or latched against the underneath edge of latch bar 20 on the carrier 1. The spring 6 connected to the upper end of the contact arm 4' exerts a lifting force upon the pivot rod 19, whereby the carrier is biased upwardly until the lower edges of carrier slots 14 engage carrier pivots 15. Thus, the bimetal, switch arm 4, and carrier 1 are movable as a unit which is rotationally biased in clockwise direction about pivot pins 15 for pressure engagement of contact 3 with the stationary contact 2.

In this position pivot rod 19. is at the left-hand end of' slots 17. Rotational movement of the bimetal independently of the carrier about the axis of the pivot rod 19' is limited by engagement of the respective latch members 2% and 28. The vertical component of spring force holds the carrier in its most elevated position. It will be noted that the line of force of the spring passes close to pivot 19, and therefore, the actual latching pressure between the latching surfaces is relatively small, depending, of course, upon the weight of the spring.

When the parts are in this position, an electric circuit is established through the breaker, from terminal 9 through contact 2 to contact 3, thence switch arm 4, from which the current traverses the bimetal 5 and pigtail 26 to line terminal 10.

The bimetal, when heated through its internal resistance by current flowing through it, expands to increase the dimension between the pivot rod 19 and latching surface 27. Since pivot rod 19 is at the left-hand end of slot 17, expansion of the bimetal is manifest as a movement of the latching surface 27 toward the right, in a direction away from latch bar 20. If the overload magnitude is sufliciently high or prolonged with respect to the magnitude of the current for which the circuit breaker is calibrated, the bimetal will expand to the point where latching surface 27 is shifted sidewisely beyond the latch bar 20 so as to escape from the restraint thereof. Similarly, if the circuit breaker is equipped with a magnetic overload protector then, even though the duration of the overload may be too short to cause heating and warpage of the bimetal, current of sufiiciently high intensity will establish a magnetic flux in the yoke 28 causing the free end of the armature 29 to be attracted magnetically. However, since the free end of the armature bears upon the edge of the carrier 1 and therefore cannot move, the magnetic attraction will be manifest as a relative sidewise movement of the yoke, and the free endwise portion of the bimetal will move with it, causing the latching surface 27 again to escape the latch bar 20.

As soon as the latching surface 27 clears the latch bar 20, the bimetal member is released for pivotal movement about the axis of the pivot rod 19 independently of the carrier. Therefore, the upper end of the contact arm is swung by the spring while the lower end, on the opposite side of the pivot pin, moves in an opposite direction (i.e., counterclockwise) carrying movable contact 3 away from the stationary contact 2. Movement of the switch arm 4 is limited by abutment of the lower end thereof against the stop 31. When uncoupled from the bimetal, the carrier 1 swings in a clockwise direction until its lower end abuts the other side of stop 31. Thus, upon occurrence of overload, the parts move from the position in which they are shown in Figure 1 to the position in which they are shown in Figure 2.. Incidental to the rocking movement of the carrier, the finger 43 on the cross wall thereof engages the projection 39 on the handle, and pivotally shifts the handle from the vertical position shown in Figure 1 to the angularly offset position shown in Figure 2 in which the handle denotes a tripped condition of the breaker.

Manual release The circuit breaker may be tripped manually to open circuit position from the closed circuit position in which it is shown in Figure 1 by moving the handle in a clock wise direction, that is, to the right as seen in Figure 1.

In movement of the handle about its pivot point 34, the edge 40 of the handle projection 38, which is normally spaced above the cross wall 13 of the carrier 1, comes into contact with the cross wall as shown diagrammatically in Figure 5. The carrier thereby is forced ment is shifted to the right by the cannning surfaces as the carrier 1 moves downwardly, whereupon the latching surface 27 of the bimetal is displaced sidewisely from the latch bar 20.

During this phase of movement, contact 3 slides across the face of the stationary con-tact 2. This friction wiping of the contact faces, which may be augmented by crowning of one or both contacts, helps maintain them in a clean condition.

Immediately upon release of the bimetal from latch bar 20, it swings in a counterclockwise direction about its pivot rod 19 under the influence of spring 6. The tension of spring 6 is also effective to shift the bimetal physically to the left until its pivot rod 19 again engages the left-hand ends of slots 17, whereupon a rotational thrust in the clockwise direction is exerted on the carrier 1 with respect to its pivots 15. At the end of this phase of operation, contact arm 4 and carrier 1 rest against the opposite sides of stop 31.

During this operation the edge 40 of the handle projection 38 is still in engagement with the upper surface of the cross wall 13 of the carrier. Thus, Figure 6 shows the relationship of the parts momentarily after the bimetal has been unlatched from the carrier, in which position the contact arm is swinging away from the stationary contact. At this time the spring is urging the carrier upwardly.

Continued movement of the handle in the clockwise direction past the point at which the bimetal becomes unlatched brings the edge 40 of the handle projection 38 to a position past edge 42 of the cross wall of the carrier, as is shown in Figure 7. This permits the carrier to move upwardly until the ends of the carrier slots 14 engage the carrier pivots 15. The circuit breaker is now in position to be relatched.

It is particularly to be noted that while the pin-and-slot connection 19-17 provides for shifting the face of latch member 27 relatively across the face of latch member 20 on the carrier to effect latch disengagement, the declination of the axis of slot 17 relative to the operating face of latch member 20 causes the latch member 27 also to move laterally away from that face, i.e., downwardly as shown, during manual releasing. Thus, instead of merely sliding under full latching pressure across the operative face of latch member 20, the operating surface of latch member 27 during manual release moves angularly or in compound direction both to the right and downwardly, away from the face of latching member 20. By this arrangement, the latch surfaces are caused to part with ease, and any undesirable deformation of the bimetal because of friction at the latching surfaces is prevented.

Relatching 0r resetting of circuit breaker To effect relatching of the circuit breaker, the handle 7 is moved manually in a counterclockwise direction, as shown by the arrow in Figure 8. This movement causes the face 41 of the handle projection 38 to engage the edge 42 of the cross wall, or the face of the flange thereon, as illustrated. Since the carrier pivots are now at the bottoms of slots 14 and the bimetal pivot rod 19 is at'the left of its slots 17, movement of the handle causes counterclockwise rotation of the carrier while the contact arm 14 is restrained against movement through its engagement with the stop 31. The bimetal element is therefore pivotal about its point of engagement with stop 31, and counterclockwise movement of the carrier exerts a thrust upon the pivot rod 19 of the bimetal to cause the bimetal to move clockwise. Thus, at the intersection of the locus of movement of the latch bar 20 with the locus of movement of latch member 27, the latch members become re-engaged as shown in Figure 9. In this connection it will be noted that the latching end of the bimetal is moving downwardly at a relatively steep angle, across the path of latch bar 20, while the latch bar 20 is moving upwardly at a slight angle, yieldably displacing the latch 27 by the amount which the two latch surfaces are to overlap one another. when latched. The bimetal, therefore, is relieved of any substantial strain or distortion as an incident of relatching. During movement of the handle 7 to the left, and because of the differences in location between the pivot axis of the handle and the pivot axis of the carrier, the surface 41 of the handle finger 38 slides relatively upwardly over the edge of.

the carrier cross Wall, the parts being so proportioned that engagement of the latch surface 27 with the latch bar 20 is effected prior to the time that the handle surface 41 moves past the edge of the carrier cross wall.

As long as the surface 41 on the handle remains in engagement with the edge of the carrier cross wall, the carrier is restrained against rotation even though the bimetal is now coupled with it. However, immediately after the handle surface 41 is moved upwardly above the edge of the cross wall, the spring 6 causes pivotal movement of the carrier and bimetal, as a coupled unit, in clockwise direction, thereby causing the contact 3 to engage the face of stationary contact 2.

From this description it will be seen that the only dimension affecting calibration of the circuit breaker is the dimension from the bimetal pivot rod 19 to the edge of the latch bar 20 with which the latching surface 27 cooperates. Under electric overload, through heating thereof or by magnetic action, the movement of the endwise portion of the bimetal increases that dimension sufficiently for the latching surface 27 to become disengaged from the latch bar 20. By virtue of this characteristic of the circuit breaker of the present invention, the bimetal 20 readily may be calibrated prior to assembly simply by adjusting the bend or configuration of the bimetal until the distance from the pivot rod to the latching surface 27 meets the gauge requirement.

A modified arrangement for calibrating the bimetal in assembly with the carrier prior to introduction of the assembly into the circuit breaker is disclosed in Figure 4. In this instance ears 49 projecting from the side walls 12 of the carrier are bent reversely upon themselves so that the inward ends of the ears 49 form the left-hand ends of slots 17. The folded ears readily may be bent to greater or lesser degree by a suitable tool to change the apparent left edge of the switch arm pivot slot 17.

The manner of cooperation of the parts permits use of a bimetal element of substantial length, which, if desired, may be of compound construction so as to be self-compensating against variations in ambient temperature. For example, throughout approximately onehalf of the length of the bimetal element the metals having different coefiicients of expansion may occupy a position reversed with respect to the position they occupy throughout the other half of the length of the bimetal.

In such construction, any increase in ambient temperature tending-to cause Warping of the free end of the bimetal in one direction is offset by warpage of the other half of the bimetal in a relatively opposite direction so that the free end portion of the bimetal, at which the latching surface 27 is positioned, remains unaffected by variations in ambient temperature.

If a simple rather than a compound type bimetal is to be used, compensation for variations in temperature may be provided by the arrangement shown in Figure 10 wherein a bimetal member 50 is fastened rigidly at its upper end, 51, to one of the side walls 12 of the carrier. The lower end of the bimetal bears upon the switch arm 4 adjacent pivot rod 19 thereof, as at 52. By constructing bimetal 59 to bend in a direction opposite to the direction of warpage of bimetal 5 on change of ambient temperature, the engagement of latching surface 27 with respect to latch bar 20 may be made to remain unchanged despite ambient temperature variations.

In a further modification, the circuit breaker may be to equipped for calibration after assembly within the case by providing a screw 53 (Figure 10) in the member for engaging the switch arm 4 adjacent the pivot rod 19 whereby adjustment of the. screw will shift the bimetal 5 relative to the latch member 20 on the carrier to alter the sensitivity of. the circuit breaker. It will also be understood that in this type of construction the member 50 for supporting the screw may be a simple piece of metal, e.g., formed as a part of the carrier, if ambient temperature compensation is not desired.

Two pole circuit breaker with common trip Where double pole service is desired, each circuit breaker of a pair, when tripped electrically, may be arranged to trip the other circuit breaker so as to open both poles. This is provided by installation of a common trip pin 54, as shown in Figures 11 and 12. The lower portion of the carrier 1 of each circuit breaker of the pair is provided with a hole 55, while the adjacent portion of the case of the circuit breaker is provided with an aperture or slot 56. The holes are located adjacent the free end of the bimetal in its latched position or, as shown, adjacent the magnetic yoke 28 carried on the bimetal. Respective endwise portions of the pin 54 are received in the holes 55 through the slots 56 of the cases of the paired circuit breakers. When both circuit breakers are in the closed position, the parts are in the relationship shown in Figure 11.

However, when one circuit breaker is tripped in response to overload, the carrier 1 of that circuit breaker moves to the left. This movement carries the end of pin 54 associated therewith in a forward direction. At the opposite endwise portion of the pin, it is fulcrumed by hole 55 in the carrier thereof, whereby the free end pushes against the bimetal to unseat the latch thereof, whereupon the second breaker of the pair is tripped mechanically in response to automatic tripping of the first breaker of the pair.

Having described my invention, I claim:

1. An electric circuit breaker comprising cooperating contacts, a shiftable current-responsive member having one of said contacts secured thereon, single spring means biasing said current-responsive member to an open position in which said contacts are disengaged and to a closed position in which said contacts are engaged and a circuit is completed through the circuit breaker and the currentresponsive member thereof, an operating handle movable to an open position and to a closed position, a movable carrier operatively coupling said current-responsive member to said handle, said current-responsive member and said carrier having interengageable latch means respectively secured thereon through which said current-responsive device is movable in unison with said carrier while maintaining said contacts engaged when said latch means are engaged and through which said current-responsive device is released for biased movement by said spring means independently of said carrier when said latch means are disengaged upon passage of overload current through said current-responsive device, guide means for shifting said current-responsive device to latch-disengaging position in consequence of movement of said carrier by said handle as said handle is moved to open position to permit said current-responsive member to snap said contacts to open position, and means for moving said carrier and said current-responsive device into position for relatching engagement of said latch means through movement of said handle to closed position.

2. An electric circuit breaker comprising cooperating contacts, a current-responsive member having one of said contacts secured thereon, said current-responsive member being biased to an open position in which said contacts are disengaged and movable to a closed position in which said contacts are engaged and a circuit is completed through the circuit breaker and the current-responsive member thereof, an operating handle movable to an open position and to a closed position, a movable carrier, means including a pivot and slot connection operatively coupling said current-responsive member to said handle, said current-responsive member and said carrier having interengageable latch means respectively secured thereon through which said current-responsive device is movable in unison with said carrier while maintaining said contacts engaged when said latch means are engaged and through which said current-responsive device is released for biased movement independently of said carrier when said latch means are disengaged upon passage of overload current through said current-responsive device, guide means for moving said current-responsive device to latchdisengaging position in consequence of movement of said carrier by said handle as said handle is moved to open position, a stop member engageable by said currentresponsive device in its movement to contact disengaging position, and means including said carrier for swinging said current-responsive device about said stop surface into position for relatching of said latch means and re-engagement of said contacts.

3. An electric circuit breaker comprising a stationary contact, a carrier, a U-shaped bimetal member having associated with one arm thereof a contact engageable with said stationary contact, means forming a pin-andslot connection associating said bimetal member with said carrier whereby said bimetal member is movable with respect to said carrier pivotally about the axis of said pin and shiftably along the axis of said slot of said pinand-slot connection, cooperating latch members on said carrier and said bimetal member engageable upon pivotal movement of said bimetal member when the pivot is at one end of said slot and disengageable upon movement of the other arm of said bimetal member in response to current overload and also in response to movement of the bimetal member relative to the carrier along said slot, means biasing said bimetal member in a direction for disengaging the contact thereon from said stationary contact and biasing the pin of said pin-and-slot connection to a position at the end of said slot, means including a handle movable to an open position, a cam surface for shifting said bimetal member relative to said carrier along the axis of said slot to disengage said latch means manually and thereby release said bimetal for movement of the contact secured thereto to contact-disengaging position, and means including a member engageable with said carrier for effecting movement of said bimetal member in counter direction to relatch the same to said carrier-and re-engage the contact secured thereon with said stationary contact against the bias of said spring means.

4. An electric circuit breaker comprising relatively movable contacts, a carrier, a current-responsive member having one of said contacts secured thereto, said carrier and said current-responsive member having interengageable latches thereon, means independent of said latches for movably coupling said current-responsive member to said carrier whereby said carrier and current-responsive means are movable as a unit while maintaining said contacts engaged when said latches are engaged, said currentresponsive member being movable independently of said carrier when said latches are disengaged, spring means biasing the unitarily coupled carrier and current-responsive member in contact-engaging direction While biasing the current-responsive member individually to contactdisengaging position, and manual release means for shifting said current-responsive member relative to said carrier against the bias of said spring means to latch-disengaging position.

5. A circuit breaker comprising relatively movable contacts, a movable current-responsive member having one of said contacts secured thereto, the said current-responsive member being connected in series relation with said contacts so as to be heated by the current of the circuit, a carrier operatively supporting said current-responsive member, the said carrier and the said current-responsive member having interengageable latches thereon, the said latches, when engaged, coupling the current-responsive member to the carrier for movement of the two in unison and the latch on the current-responsive member being disengageable from the latch on the carrier in response to flow of overload current through the current-responsive member, a spring connected to said current-responsive member for biasing the contact thereon into engagement with the other of said contacts and for moving the current-responsive member independently of the carrier when the said latches are disengaged, means effective upon movement of said carrier and current-responsive member in unison for shifting said current-responsive member against the bias of said spring to a latch-disengaging position, and a handle for moving said carrier to elfect such disengagement of said latch means.

6. A circuit breaker comprising relatively movable contacts, a movable current-responsive member having one of said contacts secured thereto, the said currentresponsive member being connected in series relation with said contacts so as to be heated by the current of the circuit, a carrier operatively supporting said currentresponsive member, the said carrier and the said currentresponsive member having interengageable latches thereon, the said latches, when engaged, coupling the current-responsive member to the carrier for movement of the two in unison and the latch on the current-responsive member being disengageable from the latch on the carrier in response to flow of overload current through the current-responsive member, a spring connected to said current-responsive member for biasing the contact thereon into engagement with the other of said contacts and for moving the current-responsive member independently of the carrier when said latches are disengaged, means efiective upon movement of said carrier and ourrent-responsive member in unison for shifting said current-responsive member against the bias of said spring to a latch-disengaging position, a handle for moving said carrier to effect such disengagement of said latch means, and a stop member positioned to be engaged by said current-responsive means in its movement to contact-disengaging position, said handle having means for moving said carrier to swing the current-responsive device connected thereto about said stop means to restore interlatching engagement of the latch members on the carrier and current-responsive means.

7. An electric circuit breaker comprising a stationary contact, a carrier, a movable current-responsive switch member operatively connected to said carrier and having a contact thereon for cooperating with said stationary contact, interen'gageable latch members coupling said currentresponsive member and carrier for movement thereof in unison while maintaining said contacts engaged, one of said latch members being shifted by movement of said current-responsive member in consequence of current overload to a posiiton in which it is disengaged from the other of said latch members, a handle having a portion engageable with said carrier, means for guiding said carrier and current-responsive member along a predetermined path of movement upon movement of said handle in one direction, secondary means for displacing said current-responsive member relative to said carrier to a latch-disengaging position in consequence of guided movement of said carrier by said first guide means, and means for dependently moving said current-responsive member and carrier to latch-engaging position upon movement of said handle in an opposite direction.

8. An electric circuit breaker comprising a stationary contact, a carrier, a movable current-responsive switch member operatively connected to said carrier and having a contact thereon for cooperating with said stationary contact, interengageable latch members coupling said current-responsive member and carrier for movement thereof in unison while maintaining said contacts engaged, one of said latch members being shifted by movement of assigns said current-responsive member in consequence of current overload to a posiiton in which it is disengaged from the other of said latch members, a handlehaving a portion engageable with said carrier, means for guiding said carrier and current-responsive member along a predetermined path of movement upon movement of said handle in one direction, secondary means engageable by said current-responsive member for displacing said ourrent-responsive member relative to said carrier to a latchdisengaging position in consequence of guided movement of said carrier by said first guide means, and means for dependently moving said current-responsive member and carrier to latch-engaging position upon movement of said handle in an opposite direction.

9. An electric circuit breaker comprising a casing having line terminals and a stationary contact in electrical connection with one of said terminals, a carrier pivotally supported by said casing and also movable in a generally linear direction transversely of its pivotal axis, the said carrier presenting a latching member, a current-responsive member pivotally associated with said carrier and also movable in a generally linear direction relative thereto along a path intersecting the path along which the said carrier is movable in generally linear direction relative to its pivot axis, the said current-responsive member having a latch member cooperable with the said latch member of said carrier and being coupled for movement in unison therewith when said latch members are engaged, the said current-responsive member having a contact engageable with said stationary contact, spring means connected to said current-responsive member to efiect pivotal movement of said current-responsive member and carrier about the pivotal axis of said carrier for engagement of said contact members, the said current-responsive member being eifective upon overload to disengage its latch member from the latch member of said carrier whereby said spring means moves said current-responsive member pivotally with respect to said carrier to disengage the contact thereof from said stationary contact, a handle member associated With said case for moving said carrier in its generally linear direction of movement, means engageable by said current-responsive member in consequence of such movement of said carrier for moving the current-responsive member relative to said carrier to a latch-disengaging position whereby said current-responsive member is released to move pivotally about its axis for eifecting contact disengagement under manual control, and means including said handle for subsequently relatching said current-responsive member to said carrier.

10. An electric circuit breaker comprising a casing having line terminals and a stationary contact in electrical connection with one of said terminals, a carrier pivotally supported by said casing and also movable in a generally linear direction transversely of its pivotal axis, the said carrier presenting a latching member, a U-shaped current-responsive member pivotally associated with said carrier and also movable physically in a generally linear direction relative thereto along a path intersecting the path along which the said carrier is movable in generally linear direction relative to its pivot axis, the said current-responsive member having a latch member on one of its arms cooperable with the said latch member of said carrier and being coupled to said carrier at the other of its arms for movement in unison with said carrier when said latch members are engaged, the said currentresponsive member having thereon at one side of its pivot axis a contact engageable with said stationary contact and spring means at the other side of its pivot axis for biasing said current-responsive member to efiect pivotal move ment of said current-responsive member and carrier about the pivotal axis of said carrier for engagement of said contact members, the said current-responsive menv her being effective upon overload to disengage its latch member from the latch member of said carrier whereby said spring means moves said current-responsive member pivotally with respect to said carrier to disengage the contact thereof from said stationary contact, a handle member associatedwith said case for moving said carrier in its generally linear direction of movement, means engageable by said current-responsive member in consequence of such movement of said carrier for moving the current-responsive member to a latch-disengaging position whereby said current-responsive member is caused to move pivotally about its axis for efiecting contact disengagement under manual control, and means including said handle for subsequently relatching said current-responsive member to said carrier.

11. An electric circuit breaker comprising relatively movable contacts, a U-shaped carrier, a current-responsive memberstraddled by said U-shaped carrier and having one of said contacts secured thereto, said carrier and said current-responsive member having interengageable latches thereon, means independent of said latches couplying said current-responsive member to said carrier whereby said carrier and current-responsive means are movable as a unit when said latches are engaged and said current-responsive member is movable independently of said carrier when said latches are disengaged, spring means biasing the unitarily coupled carrier and currentresponsive member in contact-engaging direction while simultaneously biasing the current-responsive member individually to contact-disengaging position, and manual release means for shifting said current-responsive member relative to said carrier against the bias of said spring means to latch-disengaging position.

12. An electric circuit breaker comprising relatively movable contacts, a carrier, a current-responsive member having one of said contacts secured thereto, said carrier and said current-responsive member having interengageable latches thereon, means including a pivot on said current-responsive member and a slot in said carrier engaged by said pivot independent of said latches for movably coupling said current-responsive member to said carrier whereby said carrier and current-responsive means are movable as a unit when said latches are engaged and said current-responsive member is movable independently of said carrier when said latches are disengaged, spring means connected to said current-responsive member for urging the pivot thereof to one end of said slot thereby biasing the unitarily coupled carrier and current-responsive member in contact-engaging direction while biasing the current-responsive member individually to contact-disengaging position, and manual release means for shifting said current-responsive member relative to said carrier'against the bias of said spring means to latch-disengaging position.

13. An electric circuit breaker comprising relatively movable contacts, a carrier, a current-responsive member having one of said contacts secured thereto, said carrier and said current-responsive member having interengageable latches thereon, means including a pivot on said current-responsive member and a slot in said carrier engaged by said pivot independent of said latches for movably coupling said current-responsive member to said carrier whereby said carrier and current-responsive means are movable as a unit when said latches are engaged and said current-responsive member is movable independently of said carrier when said latches are disengaged, spring means connected to said current-responsive member for urging the pivot thereof to one end of said slot thereby biasing the unitarily coupled carrier and current-responsive member in contact-engaging direction While biasing.

the current-responsive member individually to contactdisengaging position, manual release means for shifting.

said carrier. along a path lateral to the longitudinal axis,

of said slot, and a cam engageable by said pivot during:

movement of said current-responsive member in consequence of movement of said carrier for shifting said pivot axially in said slo't thereby to move said CHITBIIt-IeSPOH sive member relative to said carrier to latch-disengaging position.

14. An electric circuit breaker comprising a casing having line terminals and a stationary contact in electrical connection with one of them, a carrier, a currentresponsive member movably associated with said carrier through a pin and slot connection, spring means connected to said current-responsive member in spaced relation to the said axis of the pin of said pin and slot connection at one side thereof, a contact carried by said current-responsive member in spaced relation to the pin of said pin and slot connection at the other side thereof, the said contact being engageable with said stationary contact, the said spring means biasing the said currentresponsive member for movement of the contact thereof in a direction away from said stationary contact while simultaneously biasing the current-responsive member to one end of said pin and slot connection, the said currentresponsive member being in series electrical connection with the said line terminals whereby a current flows through it when said contacts are engaged, the said carrier and the said current-responsive member having cooperable latching members whereby the current-responsive member and the carrier are movable in unison when the said latch members are in latched engagement with one another and the said current-responsive member moves pivotally to disengage its contact from the stationary contact when said latching members are disengaged, a handle for moving said carrier and current-responsive member in unison when said latched members are engaged, stationary cam means engageable during movement of said members in unison for shifting said currentresponsive member through said pin and slot connection against the bias of said spring means to a position in which the latch member of the current-responsive device is disengaged from the latch member of the carrier whereby the current-responsive member may be released manually to separate its contact from the stationary contact, a stop surface engageable with said current-responsive member when said latch members are disengaged and about which said current-responsive member is pivotally movable, said handle including resetting means for moving said carrier in a direction to swing said currentresponsive member arcuately about said stop surface and thereby re-engage the latch member thereof with the latching member of said carrier.

15. An electric circuit breaker comprising a case having electric line terminals and a stationary contact in electrical connection with one of said terminals, a carrier associated with said case through a pin and slot connection, a current-responsive member associated with said carrier through a second pin and slot connection, the axes of the respective slots of said pin and slot connection intersecting one another, the said current-responsive member and the said carrier having cooperable latch surfaces whereby the current-responsive member is coupled to said carrier for movement in unison therewith when the said latch members are engaged, the said current-responsive member being in electrical connection with the other of said line terminals and having a contact engageable with said stationary contact, spring means biasing said currentresponsive member to eiiect disengagement of the contact thereof from said stationary contact when said latch members are disengaged, the said current-responsive member being constructed to move to a latch-disengaging position in consequence of the passage of overload current therethrough, and means for disengaging the latch members manually including a handle movably associated with said case, the said handle upon movement in one direction being engageable with said carrier to move the same along the axis of its slot connection to said case, and cam means engageable by the current-responsive member during movement thereof in unison with the carrier for shifting the current-responsive means along the slot axis of its connection with the carrier to disengage its latch from the latch of said carrier.

16. An electric circuit breaker comprising a case presenting line terminals, a stationary contact in electrical connection with one of said line terminals, a pivot, a stop surface, a movable current-responsive member having a contact thereon engageable with said stationary contact and being engageable with said stop surface upon disengagement of said contacts, a carrier movably associated with said pivot, said carrier and said current-responsive member being movably associated with each other and having interengageable latch means thereon whereby they are movable in unison when said latch means are interengaged, spring means connected to said current-responsive member for biasing said current-responsive member and carrier when coupled for movement in unison through interengagement of said latch means in a direction effecting engagement of said contacts while biasing said currentresponsive means for movement in contact-disengaging direction to effect separation of said contacts upon disengagement of said latch means, means including a handle for effecting disengagement of said latch means upon movement of said handle in one direction, said handle having means engageable with said carrier upon movement of said handle in an opposite direction to swing said carrier about its pivot thereby eifecting movement of said current-responsive member about said stop and thereby recouple said current-responsive member to said carrier through re-engagement of said latch means.

17. An electric circuit breaker comprising normally engaged stationary and movable contacts, a currentresponsive device carrying said movable contact and having a latch member spaced therefrom, a carrier associated with said current-responsive member through a pivot and slot connection at'an axis located intermediate said movable contact and said latch member, said carrier having a latch member engageable with the latch member of said current-responsive device and being movably coupled to said current-responsive device for movement of the two in unison when said latch members are engaged, spring means biasing the said current-responsive device pivotally with respect to the carrier for movement to a contact-disengaged position in consequence of separation of the latch member of the current-responsive device from the latch member of the carrier upon occurrence of electric overload, manually operable means for shifting said current-responsive device relative to said carrier through movement at the said pivot and slot connection for disengaging the latch surface of the current-responsive device from the latch surface of the carrier independently of electric overload condition, and means including said manually operable means for subsequently moving said carrier and said current-responsive member arcuately in counter directions to effect intersection and re-engagement of the respective latching members thereof whereby the current-responsive device is recoupled to said carrier.

18. An electric circuit breaker comprising a case presenting line terminals, a stationary contact in electrical connection with one of said line terminals, a pivot, a stop surface, a movable current-responsive member having a contact thereon engageable with said stationary contact and being engageable with said stop surface upon disengagement of said contacts, a carrier movably associated with said pivot, said carrier and said current-responsive member being movably associated with each other and having interengageable latch means thereon whereby they are movable in unison when said latch means are interengaged, the locus of movement of the latch means on said current-responsive member about said stop intersecting the locus of movement of the latch means on said carrier about said pivot, spring means connected to said current-responsive member for biasing said currentresponsive member and carrier when coupled for movement in unison through interengagement of said latch means in a direction eifecting engagement of said contacts while biasing said current-responsive means for movement in contact-disengaging direction to effect separation of said contacts upon disengagement of said latch means, means including a handle for efiecting disengagement of said latch means upon movement of said handle in one direction, said handle having means engageable with said carrier upon movement of said handle in an opposite direction to swing said carrier about its pivot thereby effecting movement of said current-responsive member about said stop and thereby recouple said current-responsive member to said carrier through re-engagement of said latch means.

19. An electric circuit breaker comprising a case presenting line terminals, a stationary contact in electrical connection with one of said line terminals, a pivot, a stop surface, a movable current-responsive member having a contact thereon engageable with said stationary contact and being engageable with said stop surface upon disengagement of said contacts, a carrier movably associated with said pivot, said carrier and said current-responsive member being movably associated with each other and having interengageable latch means thereon whereby they are movable in unison when said latch means are interengaged, spring means connected to said current-responsive member for biasing said current-responsive member and carrier when coupled for movement in unison through interengagement of said latch means in a direction effecting engagement of said contacts While biasing said current-responsive means for movement in contact-disengaging direction to effect separation of said contacts upon disengagement of said latch means, means including a handle for effecting disengagement of said latch means upon movement of said handle in one direction, said handle having means engageable with said carrier upon movement of said handle in an opposite direction to swing said carrier about its pivot thereby effecting movement of said current-responsive member about said stop and thereby recouple said current-responsive member to said carrier through reengagement of said latch means, said carrier having a portion in engagement with said handle when said contacts are in engagement for shifting said handle through movement of said carrier in consequence of disengagement of said latch members.

20. An electric circuit breaker comprising a stationary contact, a carrier, a U-shaped bimetal member having associated with one arm thereof a contact engageable with said stationary contact, means forming a pin-and-slot connection associating said bimetal member with said carrier whereby said bimetal member is movable with respect to said carrier pivotally about the axis of said pin and shiftably along the axis of said slot of said pin-andslot connection, cooperating latch members on said carrier and said bimetal member engageable upon pivotal movement of said bimetal member when the pivot is at one end of said slot and disengageable upon movement l '16 of the other arm of said bimetal member in response to current overload and also in response to movement of the'bimetal member relative to the carrier along said slot, means biasing said bimetal member in a direction for disengaging the contact thereon from said stationary contact and biasing the pin of said pin-and-slot connection to a position at the end of said slot, means including a handle movable to an open position, a cam surface for shifting said bimetal member relative to said carrier along the axis of said slot to disengage said latch means manually and thereby release said bimetal for movement of the contact secured thereto to contact-disengaging position, the axis of: the slot of said pin-and-slot connection being angulated relative to the plane of engagement of said latching member so as to direct the latch member on said bimetal member angularly away from the latch member on said carrier during movement of said bimetal relative to said carrier, and means including a member engageable with said carrier for effecting movement of said bimetal member in a counter direction to relatch the same to said carrier and re-engage the contact secured thereon with said stationary contact against the bias of said spring means.

21. An electric circuit breaker comprising relatively movable contacts, a carrier, a current-responsive member having one of said contacts secured thereto, said carrier and said current-responsive member respectively having interengageable latches thereon, means independent of said latches for movably coupling said current-responsive member to said carrier whereby said carrier and currentresponsive means are movable as a unit while maintaining said contacts engaged when said latches are engaged, said current-responsive member being movable independently of said carrier when said latches are disengaged, spring means biasing the unitarily coupled carrier and current-responsive member in contact-engaging direction while biasing the current-responsive member individually to contact-disengaging position, and manual release means for angularly shifting said current-responsive member in compound direction relatively away from the latch on said carrier against the bias of said spring means to disengage the latches upon movement of said carrier and current-responsive member as a unit.

References Cited in the file of this patent UNITED STATES PATENTS 2,130,368 Sachs Sept. 20, 1938 2,639,347 Rowe May 19, 1953 2,747,053 Locher May 22, 1956 2,787,682 Locher Apr. 2, 1957 2,802,080 Locher Aug. 16, 1957 2,806,103 Gelzheiser Sept. 10, 1957 2,810,048 Christensen Oct. 15, 1957 

